Milestone is reached in construction of tunnel

Aug 21 2009 by Chris Knox, The Journal

A GATESHEAD company that is building the new Tyne Tunnel has just poured the final 530m³ of concrete at its dry dock site in Wallsend on Tyneside.

VolkerStevin, which has a turnover of £85m, has finished building the four 90m long, 8m high and 15m wide tunnel sections, which required a total of 14,400m³ of concrete poured in 32 different pours, sometimes overnight, and 3,200 tonnes of reinforcement.

Five ballast tanks will now be constructed inside each of the four tunnel sections before the sections are sealed ready for flotation and submersion in early 2010.

The team have come up against a number of challenges during this part of the project, as well as working to a tight deadline, the 34m wide the dry dock provided very little working space around the sections.

Engineering challenges included the amount of reinforcement bar required and the accuracy with which it had to be placed to ensure that the tunnel was built in the correct profile to match the riverbed and riverbanks.

The consistent quality, availability and delivery of such large amounts of concrete was also a major factor in the success of the project.

The £18m contract was awarded to VolkerStevin Marine by Bouygues Travaux Publics and is only the third vehicle tunnel in the UK to be built using the immersed tube engineering technique.

When complete the tunnel sections will lie parallel to the existing Tyne Tunnel creating a two-lane carriageway in each direction.

VolkerStevin Marine is a joint venture utilising specialist skills of sister companies VolkerStevin and Volker Stevin Construction Europe - both part of Dutch based VolkerWessels.

The firm is no stranger to building large scale marine projects, having been the main contractor on the installation of Gateshead Millennium Bridge – a contract worth £17m.

Although the firm said that it was currently experiencing tougher trading conditions, it still expects to continue its growth next year and believes it can increase its sales from £85m to £140m in five years time.

John Hume, VolkerStevin Marine board member, said: “Completing the structure of the tunnel sections is a real milestone in this project. The finishing touches are now being made on the inside of the tunnel sections ready for immersion.”